--- On Fri, 10/22/10, Wesley Furr <[email protected]> wrote:
> The dead PRAM battery would make sense then...one or maybe
> both that did
> fire up needed a power cycle or so before they would come
> up - sounds like
> maybe that PRAM battery gets some charge from the
> computer? I will have to look into replacement...
The PRAM battery provides a small amount of power to the startup circuit.
There's always a little power to the ADB ports. The power button on the
keyboard shorts that to ground which activates the power supply.
68k Macs (except possibly the Quadra 900 and 950) use the PRAM battery to keep
the settings whenever they're not running, and except for ones that have a hard
power switch they draw a bit from it every time they're booted.
The Quadra 900/950 have a 5 volt supply constantly to the NuBus slots when
plugged in. Dunno if that's also used for starting up or not.
With the Power Mac line, Apple switched to getting the startup current from the
power supply. That also keeps the Parameter RAM (PRAM) settings so as long as a
Power Mac stays plugged in it's not using the PRAM battery.
--
-----
You received this message because you are a member of the Vintage Macs group.
The list FAQ is at http://lowendmac.com/lists/vintagemacs.shtml and our
netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml
To post to this group, send email to [email protected]
To leave this group, send email to [email protected]
For more options, visit this group at
http://groups.google.com/group/vintage-macs
Support for older Macs: http://lowendmac.com/services/
